Human hepatitis B virus (HBV) has been estimated to chronically infect at lest 200,000,000 people worldwide. Chronic infection has, in turn, been linked with a high incidence of progressive liver disease and a 40% life-time probability of developing liver cancer. HBV is, therefore, the leading cause of human cancer known to be associated with a virus infection. These facts, as well as the recent discovery of animal models of HBV, have led to a rapid increase i basic research on the hepadnavirus life-cycle. The traditional hepatitis B meetings, which have been dominated by clinicians and epidemiologists interested primarily in public health issues, have not proved a suitable forum for exchange of information and ideas among scientists interested in explaining the virus in molecular terms. The present series of annual meetings, begun in 1985, have proved highly successful in filling this need, and remain the only hepatitis B conference with full and equal participation by scientists at all career levels (senior scientist, postdoc, graduate student). The 1987 meeting will be attended, as in past years by virologists, immunologists, epidemiologists and clinicians engaged in basic research on the life cycle of the hepadnaviruses and on the delta agent, a viroid-like agent requiring hepatitis B virus coinfection in order to replicate. Topics to be covered will include strategies of genome replication, tissue specific control of transcription, structure and function of viral gene products, mechanisms of pathogenesis, the role of chronic infection in hepatocellular carcinoma and mechanisms of progression to the oncogenic state. The conference will consist of seven sessions of 10' oral presentations. Each session will be chaired by a knowledgeable scientist who will present a 5' introduction, stimulate discussion and help to resolve disputed issues. Additional abstracts will be presented in two poster sessions. Participation in the meeting will be solicited by direct mailing to participants in previous years, as well as by announcement in Nature, Science, Cell and Hepatology.